Build engine TUs with C++20. (#174471)

The changes:

* Creating a bit-mask with different enum values is now a warning. Fixed
offending instances.
* `char8_t` is a different type. Fixed those instances.
* Disabling modules in Objective-C requires bypassing the driver.
* Aggregate initialization fails when there are other constructors for
structs. Added explicit constructors.
* `gn format` doesn't seem to be run on erstwhile buildroot GN files.
Fixes the formatting. But can back this out since it is technically
unrelated to C++20.

DEPS

@@ -256,7 +256,7 @@ deps = {
    Var('chromium_git') + '/vulkan-deps' + '@' + '938de304bdcb33049ec39ce45f16223eb6a960b6',
 
   'engine/src/flutter/third_party/flatbuffers':
-   Var('chromium_git') + '/external/github.com/google/flatbuffers' + '@' + '0a80646371179f8a7a5c1f42c31ee1d44dcf6709',
+   Var('chromium_git') + '/external/github.com/google/flatbuffers' + '@' + '067bfdbde9b10c1beb5d6b02d67ae9db8b96f736',
 
   'engine/src/flutter/third_party/icu':
    Var('chromium_git') + '/chromium/deps/icu.git' + '@' + '1b2e3e8a421efae36141a7b932b41e315b089af8',

engine/src/build/config/compiler/BUILD.gn

@@ -116,6 +116,7 @@ config("compiler") {
     } else if (!is_ios && !is_wasm && !is_qnx) {
       cflags += [
         "-fstack-protector",
+
         # 8 is the default, but make this explicit here so that we don't have to
         # go hunting for the flag name if we ever want a value that is
         # different from the default.
@@ -300,7 +301,8 @@ config("compiler") {
     if (wasm_use_workers) {
       cflags += [ "-sWASM_WORKERS=1" ]
       ldflags += [ "-sWASM_WORKERS=1" ]
-    } if (wasm_shared_memory) {
+    }
+    if (wasm_shared_memory) {
       cflags += [ "-sSHARED_MEMORY=1" ]
       ldflags += [ "-sSHARED_MEMORY=1" ]
     }
@@ -356,9 +358,7 @@ config("compiler") {
   # Linux/Android common flags setup.
   # ---------------------------------
   if (is_linux || is_android || is_qnx) {
-    cflags += [
-      "-fPIC",
-    ]
+    cflags += [ "-fPIC" ]
 
     if (!is_qnx) {
       cflags += [
@@ -382,7 +382,7 @@ config("compiler") {
     if (target_cpu == "arm64") {
       qnx_arch_flags += [
         "-V",
-        "gcc_ntoaarch64le"
+        "gcc_ntoaarch64le",
       ]
     } else {
       assert(false, "Unknown QNX architecture")
@@ -474,20 +474,55 @@ config("compiler") {
   # Fuchsia-specific flags setup.
   # -----------------------------
   if (is_fuchsia) {
-    configs = ["//flutter/tools/fuchsia/gn-sdk/src/config:compiler"]
+    configs = [ "//flutter/tools/fuchsia/gn-sdk/src/config:compiler" ]
   }
 
   asmflags = cflags
 }
 
+# C++ modules (available and enabled by default in C++20 and above) are
+# prohibited by the style guide.
+config("cxx_disable_modules") {
+  disable_modules_flags = [
+    "-fno-modules",
+
+    # Some Clang versions do not disable ObjC modules (as tested by
+    # __has_feature(objc_modules)) when just -fno-modules is present.
+    "-Xclang",
+    "-fno-cxx-modules",
+  ]
+  cflags_c = disable_modules_flags
+  cflags_cc = disable_modules_flags
+  cflags_objc = disable_modules_flags
+  cflags_objcc = disable_modules_flags
+}
+
 config("cxx_version_default") {
   if (is_win) {
-    cc_std = [ "/std:c++17" ]
+    cc_std = [ "/std:c++20" ]
   } else {
-    cc_std = [ "-std=c++17" ]
+    cc_std = [ "-std=c++20" ]
   }
+
+  configs = [ ":cxx_disable_modules" ]
+
   cflags_cc = cc_std
   cflags_objcc = cc_std
+
+  # The following corrections are only in place for targets that have opted into
+  # the default version. These targets have not had to opportunity to upgrade to
+  # a newer version. Targets that have explicitly opted into the newer version
+  # must fix the errors they run into.
+
+  if (is_clang) {
+    extra_warning_flags_cc = [
+      # TODO(174665): Third-party dependency (Angle) needs to patched to work
+      # around this.
+      "-Wno-deprecated-this-capture",
+    ]
+    cflags_cc += extra_warning_flags_cc
+    cflags_objcc += extra_warning_flags_cc
+  }
 }
 
 config("cxx_version_11") {
@@ -528,6 +563,8 @@ config("cxx_version_20") {
   }
   cflags_cc = cc_std
   cflags_objcc = cc_std
+
+  configs = [ ":cxx_disable_modules" ]
 }
 
 config("compiler_arm_fpu") {
@@ -575,8 +612,10 @@ config("runtime_library") {
     # Add libcxx[abi]/include via cflags_cc, cflags_objcc to apply to
     # C++/Obj-C++ only. Adding them via include_dirs is problematic for Swift,
     # whose core libraries expect the Apple SDK C++ headers, module.modulemap.
-    _libcxx_include = rebase_path("//flutter/third_party/libcxx/include", root_build_dir)
-    _libcxxabi_include = rebase_path("//flutter/third_party/libcxxabi/include", root_build_dir)
+    _libcxx_include =
+        rebase_path("//flutter/third_party/libcxx/include", root_build_dir)
+    _libcxxabi_include =
+        rebase_path("//flutter/third_party/libcxxabi/include", root_build_dir)
     cflags_cc += [
       "-nostdinc++",
       "-I" + _libcxx_include,
@@ -604,9 +643,7 @@ config("runtime_library") {
 
     ldflags += [ "-nostdlib" ]
 
-    ldflags += [
-      "-Wl,--warn-shared-textrel",
-    ]
+    ldflags += [ "-Wl,--warn-shared-textrel" ]
 
     libs += [
       "c",
@@ -639,7 +676,7 @@ config("runtime_library") {
 
   # Fuchsia standard library setup.
   if (is_fuchsia) {
-    configs = ["//flutter/tools/fuchsia/gn-sdk/src/config:runtime_library"]
+    configs = [ "//flutter/tools/fuchsia/gn-sdk/src/config:runtime_library" ]
   }
 }
 
@@ -653,6 +690,7 @@ default_warning_flags_cc = []
 if (is_qnx) {
   default_warning_flags_cc += [ "-fpermissive" ]
 }
+
 if (is_win) {
   default_warning_flags += [
     # Permanent.
@@ -1013,9 +1051,7 @@ config("no_optimize") {
     # On WASM we don't want to fully deoptimize the debug build because the
     # compiled binary will have some functions with too many local variables
     # and Chrome will reject it.
-    cflags = [
-      "-O1",
-    ]
+    cflags = [ "-O1" ]
     ldflags = common_optimize_on_ldflags
   } else {
     cflags = [ "-O0" ]
@@ -1112,6 +1148,7 @@ config("prevent_unsafe_narrowing") {
       "-Wshorten-64-to-32",
       "-Wimplicit-int-conversion",
       "-Wsign-compare",
+
       # Avoid bugs of the form `if (size_t i = size; i >= 0; --i)` while
       # fixing types to be sign-correct.
       "-Wtautological-unsigned-zero-compare",

engine/src/flutter/build/secondary/flutter/third_party/flatbuffers/BUILD.gn

@@ -15,11 +15,12 @@ source_set("flatbuffers") {
     "$_src_root/include/flatbuffers/allocator.h",
     "$_src_root/include/flatbuffers/array.h",
     "$_src_root/include/flatbuffers/base.h",
-    "$_src_root/include/flatbuffers/bfbs_generator.h",
     "$_src_root/include/flatbuffers/buffer.h",
     "$_src_root/include/flatbuffers/buffer_ref.h",
+    "$_src_root/include/flatbuffers/code_generator.h",
     "$_src_root/include/flatbuffers/default_allocator.h",
     "$_src_root/include/flatbuffers/detached_buffer.h",
+    "$_src_root/include/flatbuffers/file_manager.h",
     "$_src_root/include/flatbuffers/flatbuffer_builder.h",
     "$_src_root/include/flatbuffers/flatbuffers.h",
     "$_src_root/include/flatbuffers/flex_flat_util.h",
@@ -62,18 +63,28 @@ executable("flatc") {
     "$_src_root/grpc/src/compiler/swift_generator.h",
     "$_src_root/grpc/src/compiler/ts_generator.cc",
     "$_src_root/grpc/src/compiler/ts_generator.h",
+    "$_src_root/include/codegen/idl_namer.h",
+    "$_src_root/include/codegen/namer.h",
+    "$_src_root/include/codegen/python.cc",
+    "$_src_root/include/codegen/python.h",
     "$_src_root/include/flatbuffers/code_generators.h",
     "$_src_root/src/annotated_binary_text_gen.cpp",
     "$_src_root/src/annotated_binary_text_gen.h",
     "$_src_root/src/bfbs_gen.h",
     "$_src_root/src/bfbs_gen_lua.cpp",
     "$_src_root/src/bfbs_gen_lua.h",
+    "$_src_root/src/bfbs_gen_nim.cpp",
+    "$_src_root/src/bfbs_gen_nim.h",
     "$_src_root/src/bfbs_namer.h",
     "$_src_root/src/binary_annotator.cpp",
     "$_src_root/src/binary_annotator.h",
     "$_src_root/src/code_generators.cpp",
+    "$_src_root/src/file_binary_writer.cpp",
+    "$_src_root/src/file_name_saving_file_manager.cpp",
+    "$_src_root/src/file_writer.cpp",
     "$_src_root/src/flatc.cpp",
     "$_src_root/src/flatc_main.cpp",
+    "$_src_root/src/idl_gen_binary.cpp",
     "$_src_root/src/idl_gen_cpp.cpp",
     "$_src_root/src/idl_gen_csharp.cpp",
     "$_src_root/src/idl_gen_dart.cpp",
@@ -83,8 +94,8 @@ executable("flatc") {
     "$_src_root/src/idl_gen_java.cpp",
     "$_src_root/src/idl_gen_json_schema.cpp",
     "$_src_root/src/idl_gen_kotlin.cpp",
+    "$_src_root/src/idl_gen_kotlin_kmp.cpp",
     "$_src_root/src/idl_gen_lobster.cpp",
-    "$_src_root/src/idl_gen_lua.cpp",
     "$_src_root/src/idl_gen_php.cpp",
     "$_src_root/src/idl_gen_python.cpp",
     "$_src_root/src/idl_gen_rust.cpp",

engine/src/flutter/display_list/dl_paint.cc

@@ -13,8 +13,6 @@ DlPaint::DlPaint(DlColor color)
       draw_style_(static_cast<unsigned>(DlDrawStyle::kDefaultStyle)),
       stroke_cap_(static_cast<unsigned>(DlStrokeCap::kDefaultCap)),
       stroke_join_(static_cast<unsigned>(DlStrokeJoin::kDefaultJoin)),
-      is_anti_alias_(false),
-      is_invert_colors_(false),
       color_(color),
       stroke_width_(kDefaultWidth),
       stroke_miter_(kDefaultMiter) {}

engine/src/flutter/display_list/dl_paint.h

@@ -221,12 +221,12 @@ class DlPaint {
 
   union {
     struct {
-      unsigned blend_mode_ : kBlendModeBits;
-      unsigned draw_style_ : kDrawStyleBits;
-      unsigned stroke_cap_ : kStrokeCapBits;
-      unsigned stroke_join_ : kStrokeJoinBits;
-      unsigned is_anti_alias_ : 1;
-      unsigned is_invert_colors_ : 1;
+      unsigned blend_mode_ : kBlendModeBits = {};
+      unsigned draw_style_ : kDrawStyleBits = {};
+      unsigned stroke_cap_ : kStrokeCapBits = {};
+      unsigned stroke_join_ : kStrokeJoinBits = {};
+      unsigned is_anti_alias_ : 1 = {};
+      unsigned is_invert_colors_ : 1 = {};
     };
   };
 

engine/src/flutter/fml/file_unittest.cc

@@ -343,7 +343,7 @@ TEST(FileTest, FileTestsWork) {
 TEST(FileTest, FileTestsSupportsUnicode) {
   fml::ScopedTemporaryDirectory dir;
   ASSERT_TRUE(dir.fd().is_valid());
-  const char* filename = u8"äëïöüテスト☃";
+  const auto* filename = reinterpret_cast<const char*>(u8"äëïöüテスト☃");
   auto fd =
       fml::OpenFile(dir.fd(), filename, true, fml::FilePermission::kWrite);
   ASSERT_TRUE(fd.is_valid());

engine/src/flutter/impeller/golden_tests/vulkan_screenshotter.mm

@@ -62,7 +62,8 @@ std::unique_ptr<Screenshot> ReadTexture(
                               &CGColorSpaceRelease);
   CGBitmapInfo bitmap_info =
       texture->GetTextureDescriptor().format == PixelFormat::kB8G8R8A8UNormInt
-          ? kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Little
+          ? static_cast<uint32_t>(kCGImageAlphaPremultipliedFirst) |
+                static_cast<uint32_t>(kCGBitmapByteOrder32Little)
           : kCGImageAlphaPremultipliedLast;
   CGContextPtr context(
       CGBitmapContextCreate(

engine/src/flutter/impeller/renderer/backend/vulkan/vk.h

@@ -69,6 +69,9 @@
   }
 #define VULKAN_HPP_NO_EXCEPTIONS
 
+// The spaceship operator behaves differently on 32-bit platforms.
+#define VULKAN_HPP_NO_SPACESHIP_OPERATOR
+
 #include "vulkan/vulkan.hpp"  // IWYU pragma: keep.
 
 static_assert(VK_HEADER_VERSION >= 215, "Vulkan headers must not be too old.");

engine/src/flutter/shell/platform/common/client_wrapper/standard_message_codec_unittests.cc

@@ -134,22 +134,22 @@ TEST(StandardMessageCodec, CanEncodeAndDecodeDouble) {
 TEST(StandardMessageCodec, CanEncodeAndDecodeString) {
   std::vector<uint8_t> bytes = {0x07, 0x0b, 0x68, 0x65, 0x6c, 0x6c, 0x6f,
                                 0x20, 0x77, 0x6f, 0x72, 0x6c, 0x64};
-  CheckEncodeDecode(EncodableValue(u8"hello world"), bytes);
+  CheckEncodeDecode(EncodableValue("hello world"), bytes);
 }
 
 TEST(StandardMessageCodec, CanEncodeAndDecodeStringWithNonAsciiCodePoint) {
   std::vector<uint8_t> bytes = {0x07, 0x05, 0x68, 0xe2, 0x98, 0xba, 0x77};
-  CheckEncodeDecode(EncodableValue(u8"h\u263Aw"), bytes);
+  CheckEncodeDecode(EncodableValue("h\u263Aw"), bytes);
 }
 
 TEST(StandardMessageCodec, CanEncodeAndDecodeStringWithNonBMPCodePoint) {
   std::vector<uint8_t> bytes = {0x07, 0x06, 0x68, 0xf0, 0x9f, 0x98, 0x82, 0x77};
-  CheckEncodeDecode(EncodableValue(u8"h\U0001F602w"), bytes);
+  CheckEncodeDecode(EncodableValue("h\U0001F602w"), bytes);
 }
 
 TEST(StandardMessageCodec, CanEncodeAndDecodeEmptyString) {
   std::vector<uint8_t> bytes = {0x07, 0x00};
-  CheckEncodeDecode(EncodableValue(u8""), bytes);
+  CheckEncodeDecode(EncodableValue(""), bytes);
 }
 
 TEST(StandardMessageCodec, CanEncodeAndDecodeList) {

engine/src/flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformViewsTest.mm

@@ -3812,8 +3812,10 @@ fml::RefPtr<fml::TaskRunner> GetDefaultTaskRunner() {
   CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
 
   // Draw the pixel on `point` in the context.
-  CGContextRef context = CGBitmapContextCreate(
-      pixel, 1, 1, 8, 4, colorSpace, kCGBitmapAlphaInfoMask & kCGImageAlphaPremultipliedLast);
+  CGContextRef context =
+      CGBitmapContextCreate(pixel, 1, 1, 8, 4, colorSpace,
+                            static_cast<uint32_t>(kCGBitmapAlphaInfoMask) &
+                                static_cast<uint32_t>(kCGImageAlphaPremultipliedLast));
   CGContextTranslateCTM(context, -point.x, -point.y);
   [view.layer renderInContext:context];
 

engine/src/flutter/shell/platform/darwin/macos/framework/Source/FlutterViewControllerTest.mm

@@ -939,7 +939,8 @@ TEST_F(FlutterViewControllerTest, testViewControllerIsReleased) {
   CGEventRef cgEventDiscreteShift =
       CGEventCreateScrollWheelEvent(NULL, kCGScrollEventUnitPixel, 1, 0);
   CGEventSetType(cgEventDiscreteShift, kCGEventScrollWheel);
-  CGEventSetFlags(cgEventDiscreteShift, kCGEventFlagMaskShift | flutter::kModifierFlagShiftLeft);
+  CGEventSetFlags(cgEventDiscreteShift, static_cast<uint64_t>(kCGEventFlagMaskShift) |
+                                            static_cast<uint64_t>(flutter::kModifierFlagShiftLeft));
   CGEventSetIntegerValueField(cgEventDiscreteShift, kCGScrollWheelEventIsContinuous, 0);
   CGEventSetIntegerValueField(cgEventDiscreteShift, kCGScrollWheelEventDeltaAxis2,
                               0);  // scroll_delta_x

engine/src/flutter/shell/platform/glfw/BUILD.gn

@@ -73,6 +73,8 @@ source_set("flutter_glfw") {
       "IOKit.framework",
     ]
   }
+
+  cflags_cc = [ "-Wno-deprecated-declarations" ]
 }
 
 test_fixtures("flutter_glfw_fixtures") {

engine/src/flutter/shell/platform/linux/BUILD.gn

@@ -75,6 +75,12 @@ config("relative_flutter_linux_headers") {
   include_dirs = [ "public" ]
 }
 
+config("disable_warnings") {
+  warning_flags = [ "-Wno-deprecated-volatile" ]
+  cflags = warning_flags
+  cflags_cc = warning_flags
+}
+
 source_set("flutter_linux_sources") {
   public = _public_headers + [
              "fl_binary_messenger_private.h",
@@ -99,6 +105,8 @@ source_set("flutter_linux_sources") {
 
   configs += [ "//flutter/shell/platform/linux/config:gtk" ]
 
+  public_configs = [ ":disable_warnings" ]
+
   sources = [
     "fl_accessible_node.cc",
     "fl_accessible_text_field.cc",

engine/src/flutter/shell/platform/windows/BUILD.gn

@@ -125,6 +125,8 @@ source_set("flutter_windows_source") {
     "text_input_manager.h",
     "text_input_plugin.cc",
     "text_input_plugin.h",
+    "wchar_util.cc",
+    "wchar_util.h",
     "window_binding_handler.h",
     "window_binding_handler_delegate.h",
     "window_manager.cc",

engine/src/flutter/shell/platform/windows/direct_manipulation.cc

@@ -8,6 +8,7 @@
 
 #include "flutter/shell/platform/windows/direct_manipulation.h"
 #include "flutter/shell/platform/windows/flutter_window.h"
+#include "flutter/shell/platform/windows/wchar_util.h"
 #include "flutter/shell/platform/windows/window_binding_handler_delegate.h"
 
 #define RETURN_IF_FAILED(operation)            \
@@ -259,7 +260,7 @@ void DirectManipulationOwner::Update() {
               FORMAT_MESSAGE_IGNORE_INSERTS,
           NULL, error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
           reinterpret_cast<LPWSTR>(&message), 0, NULL);
-      FML_LOG(ERROR) << message;
+      FML_LOG(ERROR) << WCharBufferToString(message);
     }
   }
 }

engine/src/flutter/shell/platform/windows/flutter_project_bundle.cc

@@ -69,11 +69,11 @@ UniqueAotDataPtr FlutterProjectBundle::LoadAotData(
     return UniqueAotDataPtr(nullptr, nullptr);
   }
   if (!std::filesystem::exists(aot_library_path_)) {
-    FML_LOG(ERROR) << "Can't load AOT data from "
-                   << aot_library_path_.u8string() << "; no such file.";
+    FML_LOG(ERROR) << "Can't load AOT data from " << aot_library_path_
+                   << "; no such file.";
     return UniqueAotDataPtr(nullptr, nullptr);
   }
-  std::string path_string = aot_library_path_.u8string();
+  std::string path_string = aot_library_path_.string();
   FlutterEngineAOTDataSource source = {};
   source.type = kFlutterEngineAOTDataSourceTypeElfPath;
   source.elf_path = path_string.c_str();

engine/src/flutter/shell/platform/windows/flutter_windows_engine.cc

@@ -274,8 +274,8 @@ bool FlutterWindowsEngine::Run(std::string_view entrypoint) {
     FML_LOG(ERROR) << "Missing or unresolvable paths to assets.";
     return false;
   }
-  std::string assets_path_string = project_->assets_path().u8string();
-  std::string icu_path_string = project_->icu_path().u8string();
+  std::string assets_path_string = project_->assets_path().string();
+  std::string icu_path_string = project_->icu_path().string();
   if (embedder_api_.RunsAOTCompiledDartCode()) {
     aot_data_ = project_->LoadAotData(embedder_api_);
     if (!aot_data_) {

engine/src/flutter/shell/platform/windows/host_window.cc

@@ -11,6 +11,7 @@
 #include "flutter/shell/platform/windows/flutter_window.h"
 #include "flutter/shell/platform/windows/flutter_windows_view_controller.h"
 #include "flutter/shell/platform/windows/rect_helper.h"
+#include "flutter/shell/platform/windows/wchar_util.h"
 #include "flutter/shell/platform/windows/window_manager.h"
 
 namespace {
@@ -317,8 +318,9 @@ std::unique_ptr<HostWindow> HostWindow::CreateRegularWindow(
     window_class.lpszClassName = kWindowClassName;
 
     if (!RegisterClassEx(&window_class)) {
-      FML_LOG(ERROR) << "Cannot register window class " << kWindowClassName
-                     << ": " << GetLastErrorAsString();
+      FML_LOG(ERROR) << "Cannot register window class "
+                     << WCharBufferToString(kWindowClassName) << ": "
+                     << GetLastErrorAsString();
       return nullptr;
     }
   }

engine/src/flutter/shell/platform/windows/wchar_util.cc

@@ -0,0 +1,42 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/windows/wchar_util.h"
+
+#include <dwmapi.h>
+
+namespace flutter {
+
+std::string WCharBufferToString(const wchar_t* wstr) {
+  if (!wstr) {
+    return "";
+  }
+
+  int buffer_size = WideCharToMultiByte(CP_UTF8,  //
+                                        0,        //
+                                        wstr,     //
+                                        -1,       //
+                                        nullptr,  //
+                                        0,        //
+                                        nullptr,  //
+                                        nullptr   //
+  );
+  if (buffer_size <= 0) {
+    return "";
+  }
+
+  std::string result(buffer_size - 1, 0);
+  WideCharToMultiByte(CP_UTF8,        //
+                      0,              //
+                      wstr,           //
+                      -1,             //
+                      result.data(),  //
+                      buffer_size,    //
+                      nullptr,        //
+                      nullptr         //
+  );
+  return result;
+}
+
+}  // namespace flutter

engine/src/flutter/shell/platform/windows/wchar_util.h

@@ -0,0 +1,29 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_WINDOWS_WCHAR_UTIL_H_
+#define FLUTTER_SHELL_PLATFORM_WINDOWS_WCHAR_UTIL_H_
+
+#include <string>
+
+namespace flutter {
+
+//------------------------------------------------------------------------------
+/// @brief      Convert a null terminated wchar_t buffer to a std::string using
+///             Windows utilities.
+///
+///             The reliance on wchar_t buffers is problematic on C++20 since
+///             their interop with standard library components has been
+///             deprecated/removed.
+///
+/// @param[in]  wstr  The null terminated buffer.
+///
+/// @return     The converted string if conversion is possible. Empty string
+///             otherwise.
+///
+std::string WCharBufferToString(const wchar_t* wstr);
+
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_PLATFORM_WINDOWS_WCHAR_UTIL_H_

engine/src/flutter/sky/packages/sky_engine/LICENSE

@@ -34764,6 +34764,22 @@ Copyright 2023 Google Inc.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 --------------------------------------------------------------------------------
+flatbuffers
+
+Copyright 2023 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+--------------------------------------------------------------------------------
 cpu_features
 
 Copyright 2023 Google LLC
@@ -34972,6 +34988,22 @@ Copyright 2024 Google Inc.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 --------------------------------------------------------------------------------
+flatbuffers
+
+Copyright 2024 Google Inc. All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+--------------------------------------------------------------------------------
 skia
 
 Copyright 2024 Google LLC

engine/src/flutter/third_party/accessibility/ax/ax_node_position_unittest.cc

@@ -113,6 +113,16 @@ class AXPositionTest : public testing::Test, public TestAXTreeManager {
 struct ExpandToEnclosingTextBoundaryTestParam {
   ExpandToEnclosingTextBoundaryTestParam() = default;
 
+  ExpandToEnclosingTextBoundaryTestParam(
+      ax::mojom::TextBoundary p_boundary,
+      AXRangeExpandBehavior p_expand_behavior,
+      std::string p_expected_anchor_position,
+      std::string p_expected_focus_position)
+      : boundary(p_boundary),
+        expand_behavior(p_expand_behavior),
+        expected_anchor_position(std::move(p_expected_anchor_position)),
+        expected_focus_position(std::move(p_expected_focus_position)) {}
+
   // Required by GTest framework.
   ExpandToEnclosingTextBoundaryTestParam(
       const ExpandToEnclosingTextBoundaryTestParam& other) = default;
@@ -157,6 +167,15 @@ class AXPositionExpandToEnclosingTextBoundaryTestWithParam
 struct CreatePositionAtTextBoundaryTestParam {
   CreatePositionAtTextBoundaryTestParam() = default;
 
+  CreatePositionAtTextBoundaryTestParam(ax::mojom::TextBoundary p_boundary,
+                                        ax::mojom::MoveDirection p_direction,
+                                        AXBoundaryBehavior p_boundary_behavior,
+                                        std::string p_expected_text_position)
+      : boundary(p_boundary),
+        direction(p_direction),
+        boundary_behavior(p_boundary_behavior),
+        expected_text_position(std::move(p_expected_text_position)) {}
+
   // Required by GTest framework.
   CreatePositionAtTextBoundaryTestParam(
       const CreatePositionAtTextBoundaryTestParam& other) = default;
@@ -203,6 +222,16 @@ class AXPositionCreatePositionAtTextBoundaryTestWithParam
 struct TextNavigationTestParam {
   TextNavigationTestParam() = default;
 
+  TextNavigationTestParam(
+      std::function<TestPositionType(const TestPositionType&)> p_TestMethod,
+      AXNode::AXID p_start_node_id,
+      int p_start_offset,
+      std::vector<std::string> p_expectations)
+      : TestMethod(std::move(p_TestMethod)),
+        start_node_id(p_start_node_id),
+        start_offset(p_start_offset),
+        expectations(std::move(p_expectations)) {}
+
   // Required by GTest framework.
   TextNavigationTestParam(const TextNavigationTestParam& other) = default;
   TextNavigationTestParam& operator=(const TextNavigationTestParam& other) =

engine/src/flutter/tools/templater/templater_main.cc

@@ -51,7 +51,7 @@ bool TemplaterMain(const fml::CommandLine& command_line) {
       rendered_template.size()};
 
   auto current_dir =
-      fml::OpenDirectory(std::filesystem::current_path().u8string().c_str(),
+      fml::OpenDirectory(std::filesystem::current_path().string().c_str(),
                          false, fml::FilePermission::kReadWrite);
   if (!current_dir.is_valid()) {
     FML_LOG(ERROR) << "Could not open current directory.";

engine/src/flutter/txt/tests/paragraph_unittests.cc

@@ -19,6 +19,7 @@
 namespace flutter {
 namespace testing {
 
+[[maybe_unused]]
 static const std::string kEmojiFontFile =
 #if FML_OS_MACOSX
     "Apple Color Emoji.ttc";
@@ -26,6 +27,7 @@ static const std::string kEmojiFontFile =
     "NotoColorEmoji.ttf";
 #endif
 
+[[maybe_unused]]
 static const std::string kEmojiFontName =
 #if FML_OS_MACOSX
     "Apple Color Emoji";